Oil field valves are widely used for production of oil and gas. One type of valve commonly used is a non rising stem gate valve. The actuator to move the gate has a handle that rotates a threaded translation sleeve, causing a non rotating stem inside the sleeve to move the gate. These valves have grease zerk fittings on the valve handles to grease the moving parts of the actuator. However, it is common for the valves to seize. Inspection of a seized valve often shows the actuator assembly is corroded or seized due to a lack of lubrication.
Once seized, they often must be disconnected from the wellhead equipment and replaced. Replacing these valves is not an easy task, requiring service professionals and a large investment. Even though some of the valves can be taken apart and reconditioned at a service facility, the servicing cost is still high considering that the valves have to be removed and transported to a service facility.